1. Polarity

2. Compound Review  Compound: a chemical combination of two or more elements  Why do elements chemically combine?  They want to achieve full energy levels  Full energy level = stability  Elements will move electrons for them to be satisfied

3. Electronegativity The attractive force that an atom of an element has for shared electrons Atoms have different electronegativities –Electrons will spend more time near atom with stronger (larger) electronegativity

4. Electronegativity EOS

5. Electronegativity

6. Polar Covalent Remember ionic bonds transfer electrons, while covalent bonds share electrons. All atoms do not attract their electrons in a bond to the same degree. One can determine the degree to which electrons are transferred or shared using the electronegativity difference

7. Polar Covalent Remember…electronegativity is a measure of an atom’s ability to attract the pair of electrons it shares with another atom. In general, metals have lower electronegativities than non metals Each atom’s electronegativities has been determined by experiences and can be found in your textbook on pg 71.

9. EN Differences To find ΔEN, subtract the EN of 2 atoms. EN must be a real number. (ie. No negatives!) If the ΔEN is: 3.3-1.7 = an ionic bond 1.6-0.5 = polar covalent 0.5-0.1 = slightly polar covalent 0.0 = non-polar covalent Determine the classification of these bonds: A) B & PB) S & OC) Li & OD) Mg & N =0.15 slight polar=0.86 polar=2.46 ionic=1.73 ionic

10. Polar vs Nonpolar Covalent Nonpolar Covalent Bonds Between two atoms with similar EN Electrons are shared equally between the two Nuclei from each atom are attracting the electrons with equal force There is little or no positive & negative charges present Polar Covalent Bonds Between two atoms with moderate difference in EN Electrons are not shared equally Results in a localized negative and positive charge The atom with higher EN will be slightly negative and other will be slightly positive Bigger the difference, the more polar the bond

11. Dipole Moments In polar molecules, we indicate their positive or negative partial charges using δ - and δ + and their polarity or “dipole moment” H δ+ F δ- H δ+ O δ- Dipole Dipole moments occur when there is an instant in time when the electrons are distinctly unequally shared.